Coordinate Keywords used in MAST FITS Files

In general, data sets archived within MAST use Right Ascension and Declination to specify target coordinates, although the keywords used to designate the coordinates vary. The table below summarizes these differences. For more information on file formats, click on the mission names.

Mission	Coordinate Keywords^*	Equinox	Units
Copernicus	RA-DEGS	2000	decimal degrees
BEFS	RA_OBJ	2000	decimal degrees
EUVE	RA_OBJ, RA_PNT	2000	decimal degrees
FUSE	RA_APER, RA_TARG	2000	decimal degrees
HUT	(none)	-	-
IMAPS	RA	2000	decimal degrees
IUE	LRA, SRA, LTARGRA, STARGRA	1950	decimal degrees
UIT	NOMRA	1950/2000	decimal degrees
WUPPE	RA	1950	decimal degrees

^*Keyword Explanation:

RA-DEGS- RA in degrees,
RA_OBJ - RA of object (provided by Guest Observer),
RA_PNT- RA of pointing (indicates slight offset needed for EUVE observations),
RA_APER- RA at center of aperture,
RA_TARG- RA of target,
LRA,SRA- IUE Large and Small Aperture RA (homogeneous coordinates derived from Simbad),
LTARGRA,STARGRA- IUE Large and Small Aperture RA provided by Guest Observer,
NOMRA- UIT nominal RA

Note that data sets containing images (e.g., UIT) also provided coordinates using CRVALn keywords.